Hi, im a new member here, I have a simple question and would like some tips on a small project im doing on my driveway. I have a narrow driveway, which can fit four cars but none next to each other. Im going to extend the width of the driveway by taking out some grass (about 5') and putting interlock, whats the best materials to use to make a bed for that interlock, considering there will be cars parked on it? Thank you!

Just one more thing to remember before you put the stone down.
Make sure you dig down deep enough to remove any top soil or dark organic looking matter. Sometimes folks have a tree root decomposing which was covered, or there was a bush or flower garden.
I have had to remove 12 inches of soil it went that deep.
The best one I ever found was the old 200 gallon gasoline tank next to the driveway which everyone had forgoten about.